<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>缓存全局变量</title>
</head>
<body>
  <!-- input:button[value=btn][id=value$]*10 -->
  <input type="button" value="btn" id="value1">
  <input type="button" value="btn" id="value2">
  <input type="button" value="btn" id="value3">
  <input type="button" value="btn" id="value4">
  <p>111</p>
  <input type="button" value="btn" id="value5">
  <input type="button" value="btn" id="value6">
  <p>222</p>
  <input type="button" value="btn" id="value7">
  <input type="button" value="btn" id="value8">
  <p>333</p>
  <input type="button" value="btn" id="value9">
  <input type="button" value="btn" id="value10">

  <script>
    function getBtn() {
      let oBtn1 = document.getElementById('btn1')
      let oBtn3 = document.getElementById('btn3')
      let oBtn5 = document.getElementById('btn5')
      let oBtn7 = document.getElementById('btn7')
      let oBtn9 = document.getElementById('btn9')
    }

    function getBtn2() {
      let obj = document
      let oBtn1 = obj.getElementById('btn1')
      let oBtn3 = obj.getElementById('btn3')
      let oBtn5 = obj.getElementById('btn5')
      let oBtn7 = obj.getElementById('btn7')
      let oBtn9 = obj.getElementById('btn9')
    }
  </script>
</body>
</html>